Effect of Silica Deposition on Zirconia/Resin Cement Bond - Pilot Study

Objectives: Silica-based nanofilm has been successfully deposited via Room Temperature Atomic Layer Deposition (RT-ALD) on glass surface. The purpose of this study was to evaluate the bond strength at the interface between yttria-stabilized zirconia (Y-TZP) and resin cement after silica deposition via RT-ALD.
Methods: Fully-sintered 3Y-TZP (MO, IPS e.max Zircad, Ivoclar Vivadent, Liechtenstein) samples (n=48) were distributed according to hydrothermal aging (0h/control or 15h - 134^_°C, 2 bar) and RT-ALD silica deposition. RT-ALD cycles consisted of exposure to tetramethoxysilane orthosilicate (TMOS - 60s) and ammonium hydroxide (NH₄OH - 10 min) vapors in 0, 10, 40, 60, 80 or 100 cycles. Treated Y-TZP specimens had microshear test cylinders (0.70mm diameter×1mm height) built on the bonded surface with resin-based cement (Multilink Automix, Ivoclar Vivadent). Bond strength was analyzed by microshear bond strength test in a universal testing machine (Instron) after 24h water-storage (37^_°C). Failure mode was evaluated using scanning electron microscopy (SEM) and classified in adhesive, cohesive and mixed. Bond strength data were analyzed by two-way ANOVA and Tukey test (α = 0.05).
Results: Neither aging nor RT-ALD had an effect on bond strength (p<0.341). Overall, higher bond strength values were observed after 10 cycles (30.10±10.66MPa) and 100 cycles (22.34±15.30MPa), regardless of aging time.
Conclusions: Silica deposition via RT-ALD may be a promising technique for the deposition of silica on Y-TZP surface. However, the methodological parameters need to be deeper investigated to obtain the expected effect of the silica deposition on bond strength.